Magnesium base alloy



Patented Nov. 12, 1940 UNITED STATES MAGNESIUM BASE ALLOY John crMcDonald, Midland; Mich, assignor to The Dow-Chemical Company, Midland, Mich, a corporation of Michigan No Drawing. Application November 13, 1939,

Serial No. 304,135

3 Claims. (01. 75-168) The invention relates to magnesium base alloys.

It more particularly concerns alloys of this nature having a high degree of formability, coupled with other improved physical properties, such as 5 high tensile and yield strengths.

Magnesium alloys are being widely used in various structural arts, where a light weight metal is highly desirable, such as for usein making castings, forgings, and the like. However, 10 the use of these metals in the rolled 1 form .to

make sheet -metal articles requiring forming operations, such as bending, drawing, and the like has not progressedas rapidly, due to the fact that in general alloys possessing good formabil- 5 ity permitting relatively sharp bends to be made without the article developing external cracks, usually have poor strength properties.

It is, accordingly, the principal object of the' invention to provide a magnesium base alloy which may be made into rolled sheet or the like,

possessing a high degree of formability or ductility, permitting it to be sharply bent, drawn, or

otherwise shaped while having improved strength characteristics.

t dv taes llbe a aet other oblec s and a an g W1 pp r n the section headed by the term annealed were obduring the course of the invention.

My invention resides in the discovery that a magnesium base alloy composed of from 0.3 to 10 per cent of silver, froml to 15 per cent of cadmium, from 0.1 to 3 per cent of manganese, and from 0.1 to 10 per cent of zinc, the balance being substantially all magnesium, is endowed with the afore-mentioned properties. While the property 35 of improved formability or ductility, associated with high tensile and yield strengths, is manifest over the entire range of composition indicated, I have found that, in general, the preferred com,- bination of properties, such as the most desirable ductility for forming operations, coupled with high tensile strength and yield strength, is ob tained when the alloy contains from 0.5 to per cent of silver, 4 to per cent of cadmium, 1.5 to 2.5 per cent of manganese, and from 0.5 to 5 per cent of zinc.

The specific proportion of each alloying metal and the total amount of the added metals to be employed in the new alloy depends upon the use for which the alloy is intended. In general, it is preferable to'use an alloy containing more than about 75 per cent of magnesium and .less than 25 per cent of the total added metal. The following table, which lists some of the properties of rolled sheet metal made from my the following description of new alloy, as well as the properties of rolled sheet of some of the related ternary alloys, illustrates the improvement in yield strength, tensile I strength, and ductility of the new alloy over the corresponding properties of the closely related alloys. In the table the per cent elongation rep-- resents the ductility or formability of the alloys.

Table Nominal composition in percent (temainder= mag- Annealed neslum) v Yield Tensile Percent strength strength Ag Cd in I bs./sq. in lbs/sq. 333

in. in.

The properties listed in the above table under similar percentages of alloying ingredients. For

example, it will be noted that the yield strength and tensile strength combined with the per cent elongation, which serves as a. measure of the duotility, shows improvement over that of the related alloys. In addition the alloys possess the characteristic of being highly resistant to corrosiv conditions.

While the new alloy is most useful in wrought form, such as sheets, due to its formability characteristics, it may also be suitably used in making castings, forgings, extruded forms, and the like. It is further pointed out that my new alloy is amenable to solution and precipitation heat treatments, which, accordingly, modify its properties.

My new alloy may be prepared by any of the methods usually employed for melting and alloying metals with magnesium, such as by adding the respective metals singly or jointly to a bath of molten magnesium, which is preferably protected from oxidation by suitable flux.

I claim:

1. A magnesium base alloy containing from 0.3 to 10 per cent of silver, from 1 to 15 per cent of cadmium, from 0.1 to 3 per cent of manganese, and from 0.1 to 10 per cent of zinc, the balance 10 being magnesium.

2. A magnesium base alloy containing from 0.5 

